Multi-action self-healing coatings with simultaneous recovery of corrosion resistance and adhesion strength

Photothermal-Responsive Wormlike Polydopamine-Wrapped Ethylene-Vinyl Acetate Copolymer toward Triple-Action Self-Healing Anticorrosion Coating

“…Sometimes, the coating adhesion strengths on substrate surfaces failed to recover effectively even after healing process, which is prone to cause the coating failure again. 16 In our design, the enhanced coating/metal interfacial interaction provided by melt EVA copolymer was confirmed by pull-off tests (Figure 8). All intact coatings immersed for 24 h exhibited high adhesion strengths, and the incorporation of PDA@EVA further improved the value (9.0 MPa) due to the chelating effect of the polydopamine component.…”

“…In comparison with separated microspheres, the adjacent connected wormlike PDA@EVA could provide more EVA copolymer to fill the scratches and improve the selfhealing efficiency at a proper temperature. 16 As depicted in Figure 1c 2 , the microspheres partly melted and connected with each other at 60 °C for 30 min. With the temperature increased to 80 °C, the copolymer completely fused into a whole (Figure 1c 3 ), which could cause phase separation in coating matrix and influence coating intrinsic properties.…”

“…As indicated by the stretching vibrations in �CH 3 (2849 cm −1 ) and �CH 2 (2927 cm −1 ), which confirmed the presence of EVA main composition, the peak at 1741 cm −1 was ascribed to the characteristic ester bonds (RCOOR′) in EVA structure. 16,45 Moreover, a new peak that appeared at 1507 cm −1 was assigned to N�H stretching of the PDA layer, thus demonstrating that PDA was coated on EVA surfaces. 46−48 As illustrated in Figure 2d, two peaks at 1438 and 1295 cm −1 were attributed to the C�H deformation in EVA copolymer and the peaks at 1060 and 1126 cm −1 were identified from C�C stretching, whereas the additional peak at 625 cm −1 was related to C�O deformation, which were in accordance with results from the relevant study.…”

“…Zhang's group reported a kind of SHACs based on EVA, while heating the entire coating is needed for the selfhealing effect, which is inconvenient in a practical environment. 16 Indeed, the healing performance of these SHACs is greatly controlled by stimulus leaching behaviors. 32 More recently, photothermal triggered shape memory of thermoplastic resin has been considered as an effective way to develop high-efficient SHACs.…”

“…18,39 It is acknowledged that a strong interfacial interaction between the coating and metal substrate is necessary for keeping satisfactory protection performance of ACs. 16,27,40 Although tremendous efforts have been conducted to improve the healing efficiency of SHACs, the focus is mainly concentrated on the restoration of corrosion resistance and coating integrity. The generation of corrosion products at the coating/metal interface and its underlying influence on the healing process have been rarely studied and elaborated.…”